I have been riding with a back pack on the zero for the last month. It has been a long time since wearing a back back commuting and I sure don't miss it. But for the time being I had to while waiting to get the rack for the DSR. Now that I have the rack it was time to install a top case to get rid of the back pack once again.
I have a Caribou luggage system on my R1150GS ADV that I also use on my Ural and my XR650L.
http://www.cariboucases.comI can change the same cases between all. The top case can now be used as a top case on the Zero.
I had a top plate for the Givi luggage that I wasn't using. I remove the plastic male clip on the plate with a dremel so I can mount the locking plate that the Caribou luggage use. It worked out pretty well.
The case is basically a rebadged Pelican 1520 case which is 25L. Caribou makes all sorts of plate systems to adapt to any bike even if they don't have a bike specific one available. You can even use any cases you want if you buy just the plates alone. My first ride to work with it will be tomorrow morning on the Zero.
*moderator edit* added width to img tags